Reed valve unit for crankcase induction engines



1954 E. G'KIEKHAEFER 2,669,979

REED VALVE UNIT FOR CRANKCASE INDUCTION ENGINES Filed Sept. 11, 1950 2Sheets-Sheet l INVENTOR.

Feb. 23, 1954 K HA R 2,669,979

REED VALVE UNIT FOR CRANKCASE INDUCTION ENGINES Filed Se t.) 11, 1950 2Sheets-Sheet 2' M i-um m /5 i s 1N VEN TOR.

filo/ways Patented Feb. 23, 1954 UNITED STATES PATENT OFFICE REED VALVEUNIT FOR CRANKCASE INDUCTION ENGINES Elmer CJKiekhaefer, Cedarburg, Wis.

Application September 11, 1950, Serial No. 184,242

9'Claims.

This invention relates to crankcase induction valve means for two-cycle,internal combustion engines, and particularly two-cylinder, alternatefiring engines.

The invention provides a crankcase induction reed valve unit whichadmits and directs the fuel mixture into the crankcase in streamsdirected radially from and arranged about the crankshaft passing throughthe crank chamber.

A principal object of'the invention is to provide a reed valve unitwhich will admit reater fuel charges more efficiently into the crankchamber.

i A further object is to provide a valve unit of maximum volumetriccapacity without necessarily increasing the volumetric capacity of thecrank chamber to accommodate the valve unit.

Another object is to provide a more efficient arrangement of the reedswith respect to the crank chamber of an engine.

A more particular object is to admit the fuel mixture into the main partof the crankcase chamber in the most direct manner whereby the enginewill receive a greater amount of fuel charge with each stroke.

These and other objects and advantages will be more fully set forth ,inthe following description of a preferred embodiment of the invention asillustrated in the accompanyin drawings.

In the drawings:

Figure 1 is a perspective View of the split bearing block adapted tosupport the center main bearing of an engine crank shaft and showing thepassages as formed therein for the crankcase induction system of theengine;

Fig. 2 is a plan view of the joined block showing the reed sections androcker arms therefor as arranged on one face of the block;

Fig. 3 is a view taken on line 3-3 of Fig. 2 showing the mating surfaceof one of the members of the bearing block;

Fig. 7 is a cross-sectional view of atwo-cycle.

alternate firing, two cylinder engine employing crankcase precompressionwith one piston cut away to show the intake ports and employing the openposition and reed valve-center bearing block shown in Figs. 7

lto4;and 4,

Fig. v8 is a. horizontal transverse section of the engine shown in Fig.7 viewing the valveblock I in plan as shown in Fig. 2.

The engine shown in the drawings includes the I cylinder block I andmember 2 which join in a transverse plane passing through the axis ofthe engine crankshaft 3. Crankshaft 3 1s supported at each end in thejournal'bearing as-' semblies 4 which close the opposite ends of thegenerally cylindrical crankcase 5 formed jointly.

Crank throws 9 and ID are spaced with respect to the crankshaft axis sothat the pistons reciprocate in opposite directions for alternate firingor with each 180 of crankshaft rotation.

Crankcase 5 is divided into the separate upper and lower crank chambersII and 12 by the bearing block [3.

In the two-cycle operation of the engine, the.

fuel mixture is admitted into the cylinders through the correspondingpassages I4 in the side of cylinder block I. Each passage l4communicates with the respective crank chamber and opens through portsl5 into the respective cylinder bore 6. The exhaust gases are dischargedthrough opposite ports 16 opening from each cylinder bore into suitableexhaust means,

not shown. The intake and exhaust ports of each bore arecontrolled bythe respective piston which opens the ports at the lower end of eachpiston stroke and otherwise closes the ports during the compression andpower stroke.

The precompression of the fuel mixture for transfer of the mixturethrough passages [4 to the respective cylinder and to displace theexhaust gases remaining in the fired cylinder is.

effected with each crank chamber by'the corresponding piston during thedownward powe stroke.

The two complementary, semi-circular bearing. members I! comprisingblock, l3 are joined by bolts 18 passing therethrough on each side of acentral axial bore l9- as shown in Fig. 3. Bore I9 is adapted to fit thecenter bearing 20 of crankshaft 3 between crank throws 9 and ID for:

the journal support of the crankshaft. The outer d1mension of members.I! fit the corresponding machined inner surfacesv of crankcase 5- todivide the latter into chambers H and [2.

The induction manifold passages 2| in memhers I! jointly registerwiththe opening22 in}: crankcasemember 2; The carburetor 23 secured theopposite end of each reed being angularly disposed to deflect the fuelmixture passing through said ports radially of said crankshaftandagainst the adjacent wall of said chamber.

3. In a two-cycle, internal combustion engine having a crankshaft and acrank chamber receiving a fuel mixture for precompression, said chamberbeing substantially cylindrical and hav ing a circular end wall spacedfrom the crank and normal to the axis of crank rotation, a series ofports opening into said chamber from said end wall for the delivery offuel mixture thereto, and a series of flexible reeds having a commoncircumferentially extending base strip secured upon said end wall, eachreed extending radially from said strip over a respective port normallyclosin the latter and being disposed to be lifted from said end walltoopen said port and to deflect .the fuel mixture entering said chamberagainst the side walls of said chamber adjacent the end wall thereof andaround the crank into the center of the chamber.

4. In an internal combustion engine having a crankcase forming a crankchamber for induction and precompression of the fuel mixture, acrankshaft having a crank throw and a journal bearing supporting saidthrow, said crankcase having an end wall adjacent the crank throw andspaced therefrom and including a complementary bearing supporting saidcrankshaft bearing and having a side wall extending from said end wallabout said crank throw, a fuel induction passage formed in saidcrankcase having a series of ports opening in said end wall, said portsbeing arranged about said bearing and opening towards said crank throw,valve reeds fixed at one end to said end wall and having a free oppositeend, the fixed ends of said valve reeds being adjacent said bearing andthe free end extending toward the side wall of the crankcase, said reedsbeing normally seated over said ports on said end wall and subject toflexing to open said ports and allow the entry of fuel mixturetherethrough into said chamber, the opposite end of each reed beingangularly disposed to deflect the fuel mixture passing through saidports against the adjacent wall of said chamber, and radially arrangedarms secured to said end wall and projecting over each of said reeds tolimit the flexing of said reeds.

5. In a two-cycle, internal combustion engine having a crankshaft and acrank chamber receiving a fuel mixture for precompression, said chamberbeing substantially cylindrical and having a circular end wall spacedfrom the crank and normal to the axis of crank rotation, a series ofports opening into said chamber from said end wall for the delivery offuel mixture thereto, a series of flexible reeds having a commoncircumferentially extending base strip secured upon said end wall, eachreed extending radially from said strip over a respective port normallyclosing the latter and being disposed to be removed from said end wallto open said port and to deflect the fuel mixture entering said chamberagainst the side walls of said chamber adjacent the end wall thereof andaround the crank into the center of the chamber, and a circumferentiallyextending member secured to said end wall over said base strip andhaving a radially projecting arm extending over each of said reeds tolimit the movement of said reeds.

6. In an alternate firing, two cylinder internal combustion enginehaving a crankcase for .in-

cit

duction and precompression of the fuelmixture, a crankshaft havingspaced crank throws and an intermediate journal, a split bearing memberassembled on said journal and dividing said crankcase into correspondingcrank chambers having side walls extending from said bearing memberabout said crank throws, a fuel induction passage formed in said bearingmember having a series of ports opening therefrominto said chambers,said ports being arranged about said journal and opening towards thecrank throws, and valve reeds having ends fixed to said bearing member,the fixed ends of saidvalve reeds being adjacent said journal and thefree end extending toward the side walls of the crank case, said reedsbeing normally seated over said ports on said member and subject toflexing to open said ports and allow theentry of fuel mixturetherethrough from said passage into the respective chamber, the free endof each reed when flexed being angularly disposed to deflect the fuelmixture passing through said ports radially of said crankshaft journaland against the adjacent wall of the respective chamber.

'7. In a two cylinder internal combustion en-' gine having a crankcase,a crankshaft having spaced crank throws and an intermediate bearingsupporting said throws, complementary bearing support members for saidcrankshaft assembled thereon and disposed to divide said crankcase intocorresponding crank chambers for induction and precompression of thefuel mixture, a fuel induction passage formed in said members and aseries of ports opening into each of said chambers, said ports beingarranged about said bearing and opening towards the corresponding crankthrow, valve reeds fixed to said members, the fixed ends of said valvereeds being adjacent said bearing and the free end extending toward theside wall of the crankcase, said reeds being normally seated over saidports on said member and subject to flexing to open said ports and allowthe entry of fuel mixture therethrough into said chamber, the oppositeend of each reed when flexed being angularly disposed to deflect thefuel mixture passing through said ports against the adjacent wall ofsaid chamber, and radially extending fixed arms secured to said memberand projecting over each of said reeds to limit the flexing of saidreeds.

8. In a two cylinder, two-cycle, internal combustion engine having acrankshaft and a crankcase therefor receiving a fuel mixture forprecompression, complementary journal bearing members assembled on saidcrankshaft to support the same and disposed to divide said crankcaseinto separate crank chambers for the respective cylinders, each memberhaving a fuel supply passage and opposite faces forming an end wall ofeach chamber, a series of ports in each member opening into each of saidchambers from said passages for the delivery of fuel mixture thereto, aseriesof flexible reeds having a common circumferentially extending basestrip secured to each face of each member, each reed extending radiallyfrom said strip over a respective port normally closing the latter andmovably disposed to open said port and to deflect the fuel mixtureentering the respective chamber against the walls of said crankcase intothe center of the chamber, and a circumferentially extending membersecured to each of said members over each of said base strips and havinga radially projecting arm extending over each of said reeds to limit themovementof said rods.

9.. In an; alternate, two:

combustion engine having a. crankcase icmindtm tion and preeompressionoithe fuel mixture, a crankshaft having spaced crankthmws: andintermediate journal, a v split. hearing assembled on said: journal anddividing saidv crankcase into corresponding chambers having, side wallsextending from sai dashearing member about saidi craniethrows, a securedtoy and exteriorly of saideranhdase adjan; cent said. member, fine]:induction passages formed. in said bearing; member having a seriesofports opening therefrom into said chambersgid ports being; arrangedabout said vjournah' and: opening towards? the crank: throws, saidcrank: case having an opening; firomg said: carburetor and: extendingcircumferentiaily' of: said member an extended distance, oppositedirections td some mnnioate with the passage thereof: and provide f fthe u l mixtur di ect y toiia number 202 of adjacent ports, and val-yesreeds hamends fixed to said bearing member; thefixed ends of tid 1 be ngidiacent said journal and.

the e nd e e d n toward theidewalls of the; crankcase, said reeds beingnormally; seated 2 8; over-said ports. on. said member and: subject toflexing. to open said ports and ailow the entryofi fuel mixturetheret-hrongh from said passage into the respective chamber; the freeend or each read when flexed beingangularly disposed to deflect: the.iueI mixture passing through said ports radially of said crankshaftjournak and against the adjacent wail of the respective chamber.

ELMER C:

References Cited in the file. of this; patent STATES PA'IEN'I'S'

